Proponents of greater budget autonomy for Washington, D.C., breathed a sigh of relief this week as they marked the end of Congress’ 35-day review period for a referendum giving the D.C. Council more control over local funds.

With neither chamber taking action to overturn it, the charter amendment allowing the city to set its own fiscal calendar and determine how it spends locally raised funds becomes law effective Jan. 1.

But supporters are still hoping for an all-clear from Congress on their progression down the path toward self-determination.

“It would be easier for all of us — congressional leaders, as well as District leaders — if Congress were to affirmatively approve what we’ve done,” Council Chairman Phil Mendelson said.

Mendelson worked with DC Vote and DC Appleseed, organizations that advocate for increased autonomy for the District, to secure a spot for the referendum on the April ballot, when it won the support of 83 percent of D.C. voters.

DC Vote Executive Director Kimberly Perry said her organization was “cautiously celebrating” but is aware that Congress still holds the authority to overturn any decisions made at the local level.

Mayor Vincent Gray and D.C. Attorney General Irvin B. Nathan, who both expressed skepticism about constitutional and legal standing, had no comment on adoption of the amendment. Del. Eleanor Holmes Norton, D-D.C., who also expressed skepticism, is holding off on commenting until receiving clarity from the two chambers’ parliamentary offices.

A recent report by the Republican majority of the House Appropriations Committee, endorsed by Speaker John A. Boehner, signaled that GOP leaders are also doubtful of the amendment’s muster. The committee “considers the recent referendum in the district as an expression of the opinion of the residents, only.” The panel approved its fiscal 2014 Financial Services appropriations bill, which contains district funding, on July 17.

The Senate Financial Services and General Government spending bill, which contains District funding, took a different tack. The bill summary said “the annual bill approves the District’s annual $12 billion local operating budget.” It makes no mention of the budget autonomy referendum. The Senate Financial Services and General Government Appropriations Subcommittee approved its version of the bill on Tuesday. The full committee is scheduled to approve it Thursday.

If the city moves forward with implementing budget autonomy, its local budget would still undergo a 30-day congressional review period like ordinary council legislation, but the city would not require an affirmative vote of Congress before spending local tax dollars. And D.C. could work on its own fiscal timeline, free from the budget standoffs and shutdown threats that frequently embroil Congress.

Fiscal 2015 would likely begin on July 1, 2014, speculated D.C. Council Budget Director Jennifer Budoff. She emphasized that the city had plenty of time for planning and preparations and that the budget would still be subject to “strong fiscal management” under budget autonomy, including a prohibition on deficit spending, limits on borrowing and a mandate that the budget be balanced.

Budoff also hopes “legal issues” will be worked out before the city proceeds.

But potential congressional actions are hard to predict.

“We do not speculate on potential future actions by the committee or by Congress,” said Jennifer Hing, a spokeswoman for House Appropriations Committee Republicans.

DC Appleseed Executive Director Walter Smith, a legal architect of the referendum, said it would be “kind of hard to see how there could be a penalty on the District because it enforces the law ... but that doesn’t mean that Congress couldn’t find some kind of way later to undo the legislation.”